Communication over fading channels with delay constraints
Berry, R.A.; Gallager, R.G.
Information Theory, IEEE Transactions on
Volume 48, Issue 5, May 2002 Page(s):1135 - 1149
Digital Object Identifier 10.1109/18.995554
Summary:We consider a user communicating over a fading channel with
perfect channel state information. Data are assumed to arrive from some
higher layer application and are stored in a buffer until transmitted.
We study adapting the user's transmission rate and power based on the
channel state information as well as the buffer occupancy; the
objectives are to regulate both the long-term average transmission power
and the average buffer delay incurred by the traffic. Two models for
this situation are discussed; one corresponding to
fixed-length/variable-rate codewords and one corresponding to
variable-length codewords. The tradeoff between the average delay and
the average transmission power required for reliable communication is
analyzed. A dynamic programming formulation is given to find all Pareto
optimal power/delay operating points. We then quantify the behavior of
this tradeoff in the regime of asymptotically large delay. In this
regime, we characterize simple buffer control policies which exhibit
optimal characteristics. Connections to the delay-limited capacity and
the expected capacity of fading channels are also discussed
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